Extended Nuclear Deterrence: What Might the Future Hold?

After years of relative indifference, extended nuclear deterrence and assurance are back. Allies want to know, now more than since the days of the Cold War, that the US nuclear umbrella will be there for them. U.S. enthusiasm, however, may be waning. So, what do allies want, and what is the United States willing to provide? 

A Brief History

The idea of extended nuclear deterrence and assurance goes back to the Eisenhower administration. In the mid-1950s, President Eisenhower put forth the idea of moving U.S. nuclear weapons to Europe to help prevent a Soviet attack on U.S. forces and NATO allies and another world war. Pursuant to Article III of the North Atlantic Treaty, NATO approved the proposal and individual NATO countries agreed to supply the physical sites and security for the U.S. nuclear weapons. U.S. personnel would be responsible for the maintenance and command and control of the nuclear weapons, but the weapons would be used in the common defense of the alliance. 

To counter critics, President Eisenhower made it clear that nuclear weapons would always remain under U.S. control through what was then Commander in Chief, United States European Command (CINCEUR) in support of Supreme Allied Commander Europe (SACEUR), who was the ultimate custodian. Allowing specific NATO allies to carry the weapons on their strike aircraft in combat if needed was the most controversial aspect of the decision, but the Department of Defense (DOD) believed it was important “to enable our Allies to use our weapons for the common defense in a timely and effective manner.” 

Some members of Congress also believed that loading U.S. nuclear weapons on allied aircraft would constitute a loss of U.S. control, rather than joint custody as the DOD had envisioned. These issues were eventually resolved, and U.S. nuclear weapons were deployed to specific NATO countries. Security, custody, and use control continued to be an issue, but by 1966 over 7,000 US nuclear land and air weapons were in western Europe, all under U.S. command and control. 

Security again became an issue in the mid-1970s, and the United States removed some of itsnuclear weapons from Europe. By the end of the Cold War, however, only a small number of NATO nations hosted U.S. nuclear weapons, and many storage sites were closed. The few remaining facilities have now been modernized by NATO with improved physical security. 

The warheads have also been modernized, and the older variants of the B61 gravity bomb retired. Production on the new B61-12 bomb was completed in 2024. It is now fully deployed to NATO, albeit in much smaller numbers, and was the second U.S. warhead to be life extended. The substantial investment in time, ten years, and money, approximately $10 billion, in the B61-12 demonstrated the previous U.S. commitment to extended European nuclear deterrence. Today, the NATO host nations remain active participants in extended deterrence and are, or will be, transitioning to the new dual capable F-35 aircraft. Of course, the B61-12s, as all previous weapons, remain under U.S. command and control. This program received broad bipartisan support, but will Europe want additional systems, and will the United States be willing to supply them?

Nuclear weapons were also deployed to the Pacific theatre on naval ships and Guam in 1951, the Philippines in 1957, and South Korea in 1958. Over the years, the number and type of nuclear weapons in South Korea varied with a peak of approximately 1,000 weapons by the mid-1960s. These deployments were never as controversial as the European deployments as there was no allied delivery participation. Indeed, the nuclear weapons in the Philippines were held largely in secret at Clark Air Base and Subic Bay Naval Base.

All nuclear weapons were removed from Guam and the Philippines in the late 1970s. The last weapons in the region were removed from South Korea as a result of the Presidential Nuclear Initiatives in 1991. At the time, there were about 100 nuclear weapons remaining in South Korea. Today the only weapons deployed to the Indo-Pacific region are those on ballistic missile submarines. 

The U.S. nuclear commitment to NATO and to Pacific allies were at the time a major part of U.S. nonproliferation goals. 

Throughout the Cold War, nuclear weapons were seen as the ultimate guarantor of security, particularly security from a nuclear attack but also security to offset an imbalance in conventional weapons. With the growth in numbers and importance also came the concern that more nations would seek nuclear weapons. President Kennedy famously predicted in 1963 that there might be ten nuclear powers by 1970 and as many as 15 or 20 by 1975.

Preventing the further proliferation of nuclear weapons technology, and therefore the proliferation of states with nuclear weapons, while guaranteeing access to nuclear power and the peaceful uses of nuclear energy, are the foundational ideas of the Treaty on the Nonproliferation of Nuclear Weapons (NPT). Most nations of the world, including the United States, agreed with this goal and have worked diligently to achieve it. When it entered into force in 1970 the NPT recognized five nuclear weapons states, the United States, Russia, the United Kingdom, France and the People’s Republic of China. U.S. extended nuclear deterrence commitments sought not only to prevent nuclear war but also served to dissuade allies from developing their own nuclear capabilities. 

Notwithstanding the NPT commitment to work toward reducing nuclear weapons, both the Soviet Union and the United States continued to grow their nuclear arsenals. The U.S. arsenal peaked at around 30,000 warheads in 1966, and the Soviet arsenal’s peaked at around 40,000 in 1986.

Post Cold War

As the Cold War ended, the Soviet Union dissolved, nuclear arsenals shrank, and Russia was no longer seen as a threat. Neither was China considered a nuclear threat, as it had a small number of nuclear weapons and a no-first-use policy. As a result, the rationale for U.S. extended nuclear deterrence and assurance was called into question. 

The Clinton administration issued the first post-Cold War Nuclear Posture Review in 1994 followed by a Presidential Decision Directive (PDD) in 1997 that provided nuclear weapons guidance to the DOD. While both of documents were classified, Robert Bell, the senior director for defense policy and arms control at the NSC, in a press conference on the new PDD said, “We have made an important change in terms of strategic nuclear doctrine in reorienting our presidential guidance away from any sense that you could fight and win a protracted nuclear war to a strategic posture that focuses on deterrence.”

In 1996, the Comprehensive Test Ban Treaty was opened for signature, and in March 1997, President Clinton and Russian President Boris Yeltsin discussed a framework for a START III Treaty that would reduce deployed strategic warheads to between 2,000 and 2,500 and include discussions on non-strategic weapons and nuclear materials transparency. The discussions were to begin as soon as Russia ratified START II. 

By the mid-1990s, the Nunn-Lugar Cooperative Threat Reduction Program was hard at work securing or destroying legacy Soviet nuclear warheads and delivery systems that were left behind in Ukraine, Kazakhstan and Belarus. These three former republics had become the third, fourth, and fifth largest possessors of nuclear weapons in the world when the Soviet Union disbanded. 

Ukraine inherited roughly 1,900 strategic warheads and between 2,650 and 4,200 tactical weapons, as well as nuclear capable bombers and intercontinental ballistic missiles (ICBMs). Kazakhstan had more than 1,400 nuclear warheads, an unknown number of tactical nuclear weapons, over 100 ICBMS, and tons of nuclear material. Belarus inherited approximately 1,000 nuclear warheads and 81 road mobile ICBMS. 

Pursuant to the terms of the Budapest Memorandum, by the end of 1994, all three countries signed the NPT as non-nuclear weapons states. All of the nuclear weapons in the three countries had been sent back to Russia by the end of 1996, further reducing the threat to Europe from Soviet nuclear weapons and Russia.

Although nuclear weapons remained the backbone of U.S. and Soviet/Russian deterrence, as their arsenals drew down, the importance of nuclear weapons, and by extension extended nuclear deterrence, was significantly reduced. New U.S. nuclear programs were deferred or cancelled, and nuclear weapons played a reduced role in national security debates. By the early 2000s, popular opinion had shifted, and some NATO countries began to question whether the United States should even have nuclear weapons in Europe. The issue was not whether extended nuclear deterrence was credible, but rather was it even needed any longer. 

In 2005, Congress engaged in some fairly contentious debates on nuclear systems and policy, including two proposals from the George W. Bush administration for two new nuclear weapons, (a robust nuclear earth penetrator (RNEP) and a reliable replacement warhead (RRW)). Given the improved relationship with Russia, arms control advocates, and many members of Congress questioned whether these systems were needed, and whether these systems would make nuclear use more likely; Congress rejected both proposals. 

An election was coming in November 2008, and there would be a new administration in office the following January. The Cold War had been over for fifteen years, the Nunn-Lugar programs in Russia were ending, global nuclear inventories were decreasing, the Russian economy had significantly recovered—although the 2008 Global Financial Crisis was a setback. The outlier to this trend was that Russia was several years into a significant effort to modernize its strategic nuclear forces, warheads, delivery systems, and infrastructure.

START II never entered into force, and the much-sought talks to reduce non-strategic nuclear arsenals never came to fruition. START, the strategic arms reduction treaty between the United States and Russia, signed in 1991, was going to expire in December 2009. When that happened, there would be nothing in its place to constrain the size of U.S. and Russian strategic nuclear arsenals. 

Even though Russia was not viewed as a threat, these shifting indicators led Congress to believe it was time for a comprehensive review and assessment of U.S. nuclear policy, posture, and force structure to serve as a guide for the new administration. As a result, Congress established a Strategic Posture Commission in 2008 to conduct an external review of nuclear policy, strategy, and force structure. William Perry and James Schlesinger served as the chair and vice chair, respectively. 

The Commission issued its report in 2009 with over 150 recommendations. Two significant themes stand out from that report. The first is that notwithstanding the Russian invasion of Georgia in August 2008, the relationship with Russia was seen as hopeful with real opportunities for collaboration and joint efforts to further reduce the size of the respective nuclear arsenals and reliance on nuclear weapons generally. In 2007, Sam Nunn, George Schlutz, Bill Perry, and Henry Kissinger had published the first of what would be five op-eds in the Wall Street Journal about the path to reducing nuclear weapons. Commission Chair Bill Perry was committed to this goal, and it is reflected in the commission report.

The second is that there was almost no mention of China in the 2009 report. 

The policy considerations on which the first Commissioners focused was the balance between a desire to lead international efforts to prevent nuclear weapons proliferation and reduce the saliency and number of nuclear weapons globally on the one hand, and the need to maintain an effective nuclear deterrent on the other. There wasn’t much talk about U.S. extended nuclear assurance and deterrence.

The commission also hoped the world would head in a direction in which proliferation and nuclear terrorism are reduced and where there is cooperation among major powers to ensure strategic stability. They “rejected the vision of a world defined over the next decade or two by . . . a renewal of competition for nuclear advantage among the major powers.” 

Just before the commission report was issued, President Obama gave his April 2009 Prague speech that also flowed from the vision articulated by Nunn, Perry, Shultz, and Kissinger. The commission embodied that optimism and hoped they would influence the new administration accordingly. 

The Obama administration’s Nuclear Posture Review, which was released on April 6, 2010, reflected much of that optimism, including the need to reduce nuclear dangers through securing weapons-usable materials and preventing proliferation. The 2010 NPR also reinforced the need for a safe, secure, effective, reliable, and credible nuclear deterrent. And although disappointing to Pacific allies, the TLAM-N, which had been removed from the U.S. Navy ships as part of the 1991 PNIs, was finally retired.

On April 8, 2010, the United States and Russia had signed the rapidly negotiated New START Treaty, which placed new limits on operationally deployed strategic systems and warheads, taking the place of the expired START 1 treaty. 

While significant problems in the U.S.-Russia relationship had begun to emerge, there remained a general perception that things were looking pretty good. There was also a view—a hope—that additional arms control agreements covering the non-strategic nuclear weapons would follow, that the total size of U.S. and Russian nuclear arsenals would be further reduced, and that the risk of nuclear confrontation would continue to diminish. 

Opposition to U.S. nuclear weapons in NATO was increasing, while Russia was still not seen as a threat and China was viewed as a growing economic power but not as a nuclear threat. 

As part of the bargain to get the Senate to give its consent to ratify New START, the Obama administration agreed to begin funding a much-needed, long delayed, modernization program for U.S. nuclear weapons, delivery systems, and infrastructure. 

Nuclear disarmament initiatives continued to expand through conferences on the humanitarian impact of nuclear weapons in 2013 and the United Nations Open-ended Working Group. In 2010, Secretary of State Hilary Clinton even offered to remove nuclear weapons from Europe in exchange for additional reductions in the Russian nuclear arsenal. Extended deterrence wasn’t particularly popular or important.

Post Post-Cold War

Fast forward to the present day, and everything has changed. The United States is facing two peer nuclear adversaries. That view of a peaceful world without nuclear weapons is a memory. Extended nuclear deterrence is once again an important aspect of deterrence. The second Strategic Posture Commission recommends that the nuclear capabilities for extended deterrence be expanded to provide the president with timely, forward deployable or deployed low yield options. The October 2023 report concluded that the United States is not prepared for the current geopolitical environment and the possibility of two simultaneous or sequential regional conflicts involving nuclear peers. More importantly, however, the commission recommended an increase in conventional capabilities to deter a conflict in the first place and avoid the possibility of nuclear conflict. Will the administration and Congress heed this advice?

China is in the midst of the largest nuclear build up and diversification in its history, developing a true nuclear triad, and deploying hundreds of land-based ICBMs. If it continues at its current pace, the Chinese nuclear arsenal could grow to 1,500 nuclear weapons by the mid-2030s. The Chinese Communist Party openly seeks to make China the preeminent global power by 2049 with a world class military by 2050. It is developing a launch-on-warning capability, referred to as “early warning counterstrike” and its long standing nuclear no-first-use policy is in conflict with its modernization approach. 

China is harassing its neighbors, wants to be the regional hegemon in the Pacific, and has shown no interest in arms control or other types of strategic stability or transparency discussion. The 2025 Worldwide Threat Report noted that three critically important points:

1.  China’s military operations to project power over Taiwan and its efforts to assert sovereignty claims in the South and East China Seas occur routinely with confrontations that increase concern of miscalculations potentially leading to conflict. . . .
2. China presents the most comprehensive and robust military threat to U.S. national security. . . .
3. China almost certainly has a multifaced, national-level strategy designed to displace the United States as the world’s most influential AI power by 2030. 

With China seeking to dominate the United States economically, scientifically, and militarily, our regional allies are worried. These ambitions have resulted in a renewed interest in US extended nuclear deterrence, both capabilities and political commitments. 

In Europe, Russia took Crimea, occupied regions of the Donbas, was caught cheating under the Intermediate Nuclear Forces treaty, and found in violation of its commitments under the Budapest Memorandum when it started its full-scale invasion into Ukraine. Russia has continued its Ukraine war and shows no signs of interest in a diplomatic solution, even after significant losses in people and capabilities by both sides. More troubling is Russia’s caviler use of nuclear coercion, consistently rattling its nuclear saber, and deploying nuclear weapons into Belarus, again. 

Loose talk about using nuclear weapons in Ukraine reportedly led to serious US concerns that Russian may have considered using a nuclear weapon in fall 2022 when the war in Ukraine was going badly. 

Russia has also threated NATO allies with nuclear attack, particularly former Warsaw Pact countries. The nuclear threats are both credible and existential and have changed NATO’s view about the threat, particularly the nuclear threat from Russia and thus the importance of U.S. extended nuclear deterrence. The seriousness of the situation led Sweden and Finland to join NATO and more recently modify their positions on wartime deployments of nuclear weapons on their territories. 

The geopolitical threat environment has come full circle, and no longer is U.S. extended deterrence seen as outdated. Now the question is how committed to extended nuclear deterrence is the United States? Are proliferation prevention and nuclear deterrence in Europe and the Indo-Pacific a priority for U.S. nuclear deterrence? Is the United States looking for greater participation in traditional extended deterrence or the actual development and deployment of nuclear weapons by allies?

In response to US uncertainty, NATO is stepping up its commitment to support U.S. nuclear weapons in Europe. Some NATO nations would like to join the list of nations hosting U.S. nuclear weapons and participate in the NATO dual-capable aircraft (DCA) mission. Others have increased their participation in nuclear exercises and considered the possibility of being dispersal bases in the event of a conflict; NATO has reiterated its commitment to nuclear deterrence and worked diligently to raise its so-called “nuclear IQ.”

Similarly, the United Kingdom, which has its own independent submarine-based strategic nuclear deterrent, has returned to the DCA mission with F-35s. In 2021, it announced an increase in the number of nuclear weapons in its arsenal to a cap of 260. The UK is also in the midst of a multi-year nuclear modernization effort to replace its existing Vanguard-class ballistic submarines with a new Dreadnought-class and developing a new nuclear warhead for the Trident ballistic missile, a joint U.S.-UK program.

France recently announced that it, too, was increasing the size of its nuclear arsenal and entered into a new cooperative agreement with the UK. French actions are not solely motivated by Russia. As President Macron noted in his March 2, 2026, speech at Longue Naval base, China is building up its military capabilities to compete with the United States, North Korea is supporting Russia in its war, and the new alliance treaty between Russia and China raises real but uncertain ramifications for Europe. He is clear that France can no longer “consider threats in isolation” and that “nuclear threats are growing and diversifying” and are increasingly interconnected.”

President Macron also announced a new policy and strategic concept, forward deterrence, that could allow NATO countries to participate in French nuclear activities, as well as the possibility of “temporary deployment of elements of our strategic air forces to allied countries.” 

The new policy is no doubt derived from his concern about the U.S. alliance commitment. “At a time when our certainties have been shaken, where our adversaries are growing bolder, where alliances face headwinds, France’s deterrent, must remain a constant.” 

As a result of the growing concern about the expanded threat from Russia and France’s conclusion that a war in the Indo-Pacific can no longer be viewed as isolated from Europe, France and the UK entered into the Northwood agreement in July 2025. This agreement allowed for the first time UK attendance at a French strategic air forces exercise. Through this agreement, President Macron also “asserted our joint solidarity with the Europeans.” 

Macron went on to describe the current political situation in a reference to the upcoming May NPT Review Conference. “The Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons will be held in May to a backdrop heavy with threats, with the concerning advances of the North Korean programme, the Iranian crisis, and the growing attempts of all of those who, in Asia, Europe and elsewhere, are seeking alternatives to the security guarantees that they thought they could rely on.”

A not-so-subtle reference to the fear that now, when U.S. nuclear deterrence is needed most, it might not be there—thus Europe must look at European nuclear deterrence.

The unease that NATO and Indo-Pacific allies are feeling about the U.S. political commitment stems from senior U.S. officials’ comments as well as the new National Security and National Defense Strategies (NSS, NDS). There is very little about nuclear deterrence in the NDS and basically nothing about extended nuclear deterrence and assurance. The National Defense Strategy provides a bit more clarity about the U.S. commitment to the security of the Indo-Pacific, and a brief reference to extended nuclear deterrence in NATO.

While the NDS apparently sees Russia’s nuclear, cyber, undersea, and space forces as focused on the U.S. homeland and not Europe, the NDS does state that it will “continue to play a vital role in NATO itself.” 

The NDS acknowledges that the nuclear forces of North Korea could be used against both Japan and Korea and presents a growing threat to the United States. Presumably, this means that U.S. nuclear extended deterrence will be supported in the Indo-Pacific. One indicator of this is the accelerated U.S. program to build and deploy a limited operational nuclear Sea Launched Cruise Missile (SLCM-N) by 2032 on a Virginia-class submarine. The SLCM-N is designed to provide theatre nuclear capability, primarily in the Indo-Pacific and enjoys bipartisan support in Congress.

Ambiguity remains, however, in the European bullet under the third line of effort in the NDS: Increase Burden Sharing with U.S. Allies and Partners. Although subtle, the language—“the Department will therefore incentivize and enable NATO allies to take primary responsibility for Europe’s conventional defense with critical but more limited U.S. support”—can be construed to read that the U.S. extended nuclear deterrence and assurance remains intact, and that the United States will retain its nuclear commitment to NATO. This reading would be consistent with Under Secretary of War for Policy Elbridge Colby’s comments at the NATO Ministerial meeting in Brussels, where he reaffirmed U.S. extended nuclear deterrence in Europe.

The Korean Peninsula bullet is more opaque as it states that “South Korea is capable of taking primary responsibility for deterring North Korea.” This sentence ends with the same phrasing as found in the Europe bullet, “with critical but more limited US support.” While the phrase in the Europe bullet seems to apply to nuclear capability, it appears to apply to the full scope of deterrence in the Korean Peninsula context. Hopefully, this reading misunderstands the intent, and the NDS is not viewed as an invitation to Korea to develop an indigenous nuclear weapon. This is particularly concerning as Korea has openly discussed the possibility of a Korean nuclear weapon. 

Concerns over China’s growing conventional and nuclear capabilities have led even Japan’s Prime Minister to put forward the idea that Japan might change its policy of prohibiting U.S. warships with nuclear weapons from making port calls. This notion could prove interesting when the Navy SLCM-N is deployed on Virginia-class submarines.

While the classified versions of both documents may, I am told, include more discussion of nuclear issues generally, considerably more open clarity is needed to assure allies and reinforce the U.S. commitment to extended nuclear deterrence. Our allies, and indeed the world, can only hope it is forthcoming to avoid a new threat of global proliferation.

What are U.S. extended deterrence options in the Indo-Pacific, assuming the capability and credibility are sufficient to deter an indigenous nuclear weapon, which would come with great fiscal and political cost? Options could include:

• Forward base air-launched nuclear weapons, or at least demonstrate the ability to do in a crisis through exercises. These exercises were included in the Obama NPR but never executed.
• Continue bomber demonstrations via bomber task force missions, including B-1s, B-2s, and B-52s, and when available the B-21.
• Expand the number and type of theatre-based systems that would be deployed by U.S. forces on U.S. platforms to the region. Should the PNIs be reversed for surface ships as well as fast-attack submarines? 
• Continue extended deterrence dialogues to ensure Indo-Pacific allies view US extended deterrence both politically and militarily credible.
• Conduct exercises with Korea and Australia to understand the application of conventional support to nuclear forces.

What might Indo-Pacific allies do to support US extended deterrence, ensure that it remains a U.S. priority, and is seen as credible by allies and adversaries? Options could include:

• Commit to financial support for forward-deployed nuclear systems, such as base security and support, to encourage the United States to deploy nuclear weapons on their territories either permanently or in the event of a crisis.
• Fund U.S. nuclear weapons modernization for use in the Indo-Pacific theatre in exchange for an assured U.S. political commitment to extended deterrence.
• Urge the United States to re-deploy nuclear weapons on Guam.
• Conduct regional exercises of US dual-capable aircraft. 
• Consider participation in DCA missions with the United States supplying the nuclear delivery vehicle in a crisis.
• Indo-Pacific allies should clearly identify what options they would want for a deterrent tailored specifically to their threat picture.

Whatever the United States and its Indo-Pacific agree upon, these options must be seen as credible by China, North Korea, and Russia on the one hand, but not as destabilizing on the other. 

Madelyn Creedon has had a long career in U.S. government service, most recently as principal deputy administrator of the National Nuclear Security Administration (NNSA) within the Department of Energy.

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